Block-copolymers containing poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and polycarbonate of bisphenol A (PC) segments were employed as compatibilizers in polystyrene (PS)/PC blends. Block-copolymers were prepared starting from oligomeric diols-terminated PPO and PC. The poly(phenylene ethers) was obtained by oxidative coupling of 2,6-dimethyl-phenol in presence of tetramethyl bisphenol A. The copolymers were obtained with a chain extension reaction between the starting oligomers using bischloroformate of bisphenol A or phosgene as coupling agent. PS/PC blends, cast from chloroform solutions or mixed by melt, were studied by differential scanning calorimeter (DSC), dynamic-mechanical thermal analysis (DMTA), and optical microscopy (OP). The thermal and morphological analyses showed a clear compatibilization effect between PS and PC, if PPO-PC copolymer is added when blending is performed in the melt; in addition, also mechanical properties are increased when compared with blends without PPO-PC. (c) 2006 Wiley Periodicals, Inc.